\begin{verbatim}
sage: S = AlphabeticStrings()
sage: K = S('UVLOIDTGKYZCRHBPMJQWXNFSAE')
sage: E = SubstitutionCryptosystem(S)
sage: E.inverse_key(K)
YOLFZWHNERICQVDPSMXGABTUJK
sage: L = E.inverse_key(K)
sage: E.en
E.enciphering  E.encoding     
sage: E.enciphering(K,L)
ABCDEFGHIJKLMNOPQRSTUVWXYZ
sage: E.enciphering(L,K)
ABCDEFGHIJKLMNOPQRSTUVWXYZ
\end{verbatim}
